Double-hand unit

ABSTRACT

A double-hand unit adapted to be secured to the wrist part of an industrial robot and to be used for gripping shaft works or the like is disclosed. The double-hand unit comprises two hand units (2, 3) comprising at least two pairs of fingers (2-1, 2-2 and 3-1, 3-2), respectively, and being disposed in a back-to-back relationship with the respective opening sides of the fingers directed in opposite directions with each other. The driving mechanisms for operating the associated fingers of the hand units (2, 3) are disposed one over the other along a plane including the fingers.

DESCRIPTION

1. Field of the Invention

This invention relates to a hand unit for industrial robots which iscapable of loading a work on a machine tool and unloading the same fromthe machine tool, and more particularly to a double-hand unit capable ofgripping shaft works and the like.

2. Background Art

A double-hand unit is employed by a work loading and unloading robotassociated with a machine tool in order to reduce the idle time of themachine tool, wherein one hand unit unloads a finished work while theother hand unit grips the next work to be machined, and then thedouble-hand unit is reversed to load the next work on the machine tool.

For this purpose, it is usual to constitute a double-hand unit byarranging two hand units along the axial direction of the grippers;however, in the case of an arrangement for handling shaft works, such anarrangement is impracticable due to the axially elongated shape of theshaft works, and also the hand unit is incapable of being reversedwithin the configuration of the machine tool.

Although there is only a limited space available in front of and underthe chucking head of a machine tool, there is a substantially infinitespace in the upward direction above the chucking head.

DISCLOSURE OF THE INVENTION

Accordingly, it is an object of the present invention to provide adouble-hand unit capable of loading and unloading works quickly throughthe utilization of the space extending above the chucking head.

According to the present invention, there is provided a double-hand unitcomprising two hand units, each including at least a pair of fingers,characterized in that the two hand units are disposed back to back, i.e.with the back of one hand adjacent the back of the other hand and theirgripping openings facing in opposite directions, with the opening sidesof the respective pairs of fingers directed in opposite directions andin that the driving units for operating the fingers of the respectivehand units are disposed along the plane including the fingers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred industrial robot to whichthe double-hand unit of the present invention can be applied favorably;

FIG. 2 is a side elevation of a double-hand unit for shaft works,embodied according to the present invention;

FIG. 3 is the top plan view of FIG. 2; and

FIG. 4 is a side elevation of the respective driving mechanisms foroperating the fingers of the hand units.

BEST MODE OF CARRYING OUT THE INVENTION

FIG. 1 is a perspective view of a preferred industrial robot to whichthe double-hand unit of the present invention can be applied favorably.In the industrial robot as shown in FIG. 1, an arm 1 is adapted to becontrolled by a servomechanism so as to perform a horizontal linearmotion along the X-axis, a swiveling motion in a vertical plane alongthe course A between the horizontal position and the vertical position,a twisting motion in a vertical plane from the vertical position alongthe course B, a vertical linear motion along the Z-axis and a swivelingmotion in a horizontal plane along the course C. The turning motion ofthe wrist part about the α-axis can be controlled between 0°/90° and0°/180° positions.

FIG. 2 is a side elevation of a double-hand unit for shaft worksembodied according to the present invention and FIG. 3 is the top planview thereof.

Referring to FIGS. 2 and 3, there are shown fingers 2-1 and 2-2 andgripping members 2-3 and 2-4 of a first hand unit 2 and fingers 3-1 and3-2 and gripping members 3-3 and 3-4 of a second hand unit 3. Thegripping center axes P1 and P2 of the first and second hand units,respectively, are parallel with each other and spaced by a predetermineddistance. The first and second hand units 2 and 3 are disposedsubstantially in a back-to-back relationship with the respective backsof the fingers 2-1 and 3-1 disposed closely to each other so that theopening sides of the fingers 2-1 and 2-2 of the first hand unit 2 andthe opening sides of the fingers 3-1 and 3-2 of the second hand unit 3are directed upward and downward respectively. A reference numeral 4designates a base section of the double-hand unit. In order to form thebase section in the minimum possible dimension along the gripping centeraxes, the respective driving mechanisms for driving the fingers of thehand units are installed within the base section 4 in a verticalrelationship (FIG. 2) as hereinafter described, namely, along a verticalplane including the fingers. The double-hand unit is secured to thewrist of a robot by means of a joint 5.

FIG. 4 illustrates the driving mechanisms for operating the fingers ofthe double-hand unit. The driving mechanism for the first hand unit andthe driving mechanism for the second hand unit are entirely identical inconstruction, except that they are symmetrical with each other and aredisposed in a vertical relationship along a vertical plane including thefingers or a plane within which the fingers operate. There are alsoshown electromagnetic valves 41 and 41', air cylinder mechanisms 42 and42', parallel guide rods 43, 43', 44 and 44', the respective bosses 45,45', 46 and 46' of the fingers, link plates 47 and 47', pivot shafts 48and 48', limit switches 50, 50', 51 and 51', and dogs 52 and 52'.

The manner of operation of the first hand unit will be describedhereinafter. In FIG. 4, the fingers 2-1 and 2-2 are in the fully openposition and the limit switch 50 is actuated by the dog 52 so that thisfully open position is detected. When the piston rod of the air cylindermechanism 42 is pushed out through the operation of the electromagneticvalve 41, the boss 45 of the finger 2-2 connected to the piston rodmoves rightward along the guide rod 43, while the link plate 47 turnsabout the pivot shaft 48 to cause the boss 46 of the finger 2-1 to moveleftward along the guide rod 44, thus the fingers 2-1 and 2-2 are causedto move to the fully closed position. This fully closed position isdetected by the limit switch 51. When the electromagnetic valve 41 isoperated in the opposite direction, the reverse operations of thosemembers and mechanisms are effected so that the fingers 2-1 and 2-2return to the fully open position, as illustrated in FIG. 4. The mannerof operation of the second hand unit is entirely identical with that ofthe first hand unit.

It is obvious that, according to the present invention, the respectiveopening sides of the fingers of the two hand units 2 and 3 are arrangedso as to be directed in the opposite direction to each other and to bedirected upward and downward respectively with their backs disposedback-to-back to each other; thus, the present invention provides adouble-hand unit capable of quick loading and unloading of a work andutilizing the space above the chucking head of a machine tool.Furthermore, the dimension of the double-hand unit along the grippingcenter axes can be reduced owing to the vertical arrangement of thedriving mechanisms for operating the respective fingers of the handunit, in which the driving mechanisms are disposed one above the other.

We claim:
 1. A double-hand unit for an industrial robot, adapted forhandling shaft work, comprising:a base section having therein a thinelongated mounting space, and having thereon a joint for attaching saidunit to an arm of said industrial robot; two hand units individuallyoperatively mounted on said base section, each said hand unit comprisingan outer finger extending outward from said base section and an innerfinger disposed outside and adjacent to said base section, said outerand inner fingers of each hand unit defining therebetween a grippingcavity having an opening; finger drive means comprising two finger drivemechanisms arranged side by side in said mounting space, each arrangedto drive a respective associated hand unit, each said drive mechanismcomprising a pair of parallel guide rods, one having slideably mountedthereon said inner finger of said associated hand unit and the otherhaving slidably mounted thereon said outer finger of said associatedhand unit, and air cylinder mechanism arranged between said pair ofparallel guide rods and operatively connected to one of said fingers,and a centrally pivoted link plate having one end connected to saidinner finger and the other end connected to said outer finger, said linkplate being arranged to cause said inner and outer fingers to slide inopposite directions on said guide rods and thereby cause closing andopening of said fingers upon actuation of said air cylinder mechanism;and said two hand units being disposed in back-to-back relationshipwhereby said outer fingers are positioned adjacent to each other andsaid gripping cavity openings are directed in opposite directions fromone another.
 2. A double-hand unit as claimed in claim 1 wherein eachfinger drive mechanism comprises a pair of limit switches for detectingclosing and opening of its associated hand unit, and a dog memberattached to one of said fingers for actuating said limit switches.
 3. Adouble-hand unit as claimed in claim 1, wherein said inner and outerfingers of each hand unit are provided with diametrically confrontinggripping members for tightly gripping said shaft work.